For those who just starting up and find it hard to find specifically some rare collectibles from where they should be dropped, here’s the ‘secret well’ I dug from…..

guess what…

THE TRAIN STATION!!

Instead of wasting your energy into other buildings, try spending all your energy on action/task at Train Station you had already, and see what’s coming out.
You wouldn’t believe that your Train station not just drops the collectibles they should!